Device for hydrofoil crafts suitable to remove from the beginning the transversal listing moments

ABSTRACT

The invention prevents the effects of transversal listing moments on the hull of a hydrofoil craft by providing at least one hinged strut between the hull and a wing as well as control and sensing means. The sensing means sense list causing forces and/or list causing flow and the control means tilt the respective hinged strut in response to the sensing means instantaneously into such an angular position that the listing moments are eliminated even before they can become effective on the hull.

United States Patent 1 Guidii 1 Jan. 16, 1973.

Inventor:

Italy Cantiere Navaltecnica S.p.A.,' Anzio, Rome, Italy [22] Filed:Sept. 28, 1970 [21] Appl. No.2 75,945

[73] I Assigneei Foreign Application Priority Data Vinicio Guidi, Marinadi Carrara,

[56] References Cited UNITED STATES PATENTS 3,270,699 9/1966 Bush 14/665H Primary Examiner-Trygve M. Blix Attorney-W. G. Fasse [57] ABSTRACT Theinvention prevents the effects of transversal listing moments on thehull of a hydrofoil craft by providing at least one hinged strut betweenthe hull and a wing as well as-control and sensing means. The sensingmeans sense list causing forces and/or list causing flow and the controlmeans tilt the respective hinged strut in response to the sensing meansinstantaneously into such an angular position that the listing momentsare eliminated even before they can become effective on r 8 Claims, 12Drawing Figures om. 4, 1969 Italy ........7364 A/69 Oct. 31, 1969 Italy.7419 A/69 [52 US. Cl. ..l14/66.5 H [5 I] Int. Cl. ..B63b 1/28 the hull.[58] Field of Search ..1 14/665 H 5' I l V7 PATENTEDJAN 16 I975 SHEET 10F 3 INVENTOR EQNICIO GUIDI QQQ M.

ATTORNEY PATENTEDJAR 16 1975 SHEET 2 [IF 3 INVENTOR VINICIO GUIDIATTORNEY PATENTEDJAN 16 ma 3. 710.747

SHEET 3 [IF 3 FIG. II

5 X g x DEVICE FOR HYDROFOIL CRAFTS SUITABLE TO REMOVE FROM THEBEGINNING THE TRANSVERSAL LISTING MOMENTS BACKGROUND OF THE INVENTIONtransversally and longitudinally by gyroscopic stabiliza- I tion meanswhich control, through electronic-hydraulic actuation elements, theflaps of the supporting wings. The hull of such crafts is connected toits immersed wings through vertical struts which are rigidly attached tothe hull thus forming an integral part of the hull. These struts are themain source of transversal listing effects to which the hull issubjected. In fact, the presence, e.g., of a horizontal orbital motioncauses on the immersed vertical planes of said struts a reducing Fwhich, multiplied by the vertical distance Z between the center ofgravity G of the hull and the plane in which said force F is effective,results in a transversal dynamic listing moment which must be balancedcompletely by the straightening moment. The same balancing is requiredwith regard to static listing moments.

In a conventional geometrical form as shown in FIG.

I 1, the vertical struts are transversally or laterally arranged one oneach side of the hull, and the distance B between the struts defineswith forces A? the straightening moment MR whereby AP is the differenceis lifting caused by the opposite action of the flaps of the supportingwings; that is MR APB. The flying height H, that is the distance betweenthe bottom of the hull and the eater surface, to which Z isproportional, defines the degree of sea roughness which the hydrofoil isable to overcome and thus its efficiency degree with respect to the waveheight.

Therefore, it is an advantage to increase said flying height H becausethis increases the operational efficiency of the craft. However, effortsto increase the flying height of presently known crafts, which height israther limited, have resulted in increased listing moments whichdependboth on Z and F, the latter when caused by orbital motionsincreasing together with the increase of the flying height H or theheight of the wave to be passed over. Consequently, for lifting thehydrofoil crafts even more above the water surface, it is necessary toincrease the straightening moment MR comprising a constant factor B anda variable factor AP. Such increasing of'the straightening moment has atpresent reached its last hydrodynamically feasable possibilities.Therefore, a significant increase in the flying height cannot beattained by the systems presently used. Accordingly, prior art hydrofoilcrafts must bear the listing effects before they can be balanced wherebya rather hard navigation and substantial stresses of the boat structureresult.

OBJECTS OF THE INVENTION In view of the foregoing the invention aims atachieving the following objects:

to remove the above drawbacks;

to prevent the effect of or to remove transversal listing moments,especially in hydrofoil crafts due to a horizontal orbital motion ofwaves;

to increase the flying height by increasing the length of the struts andconsequently the sea worthiness;

to prevent or remove such listing moments from the very beginning, thatis, before these moments become effective on the hull; g

to prevent or remove dynamic and/or static listing moments produced bythe transversal component of the horizontal orbital motion of the waves;

to assure a substantially heigher flying height of hydrofoil craftswithout the need for increasing the balancing or straightening momentspresently available in known hydrofoil crafts;

to provide a much more comfortable ride and smoothness of navigationeven where the flying height merely corresponds to presently availableflying heights;

to substantially increase the navigational stability of hydrofoil craftsin the longitudinal as well as in the transversal direction relative tothe craft;

to increase the efficiency and operability of hydrofoil crafts so thatthe steering becomes easier;

to reduce the stresses to which hydrofoil crafts are subjectedwhile inoperation on transversally effective rough seas;

to provide movable struts or fixed struts with movable flaps on thetrailing edge of the struts for the wings of hydrofoil crafts regardlesswhether the wings are fully or partly immersed, and suitable as bowand/or stern struts;

to provide means for controlling the movement of movable struts or'ofmovable strutflaps in hydrofoil crafts in response to force capable ofcausing listing moments.

SUMMARY OF THE INVENTION The list preventing device according to theinvention comprises one or more tiltable struts which are hinged to thehull to be tilted about a vertical axis, and control means for thetiltable struts, as well as sensing means for sensing any forces and/orflowwhich may cause tilting moments. The controlmeans are operativelyconnected to the sensing means and to the respective strut forinstantaneously tilting the strut into an angular posi- 7 tion whichcorresponds to the instantaneous angle included between the forwarddirection of motion of the craft and a resultant of a forward andlateral or transversal speed component whereby any operativedisadvantages and restrictions are removed because the varioustransversal dynamic and/or static listing moments are immediatelyremoved, that is before the hull receives them. Therefore, much higherflying heights are obtained with the same straightening moments presentin known hydrofoil crafts. Further, a considerably better comfort andsmoothness of navigation is achieved at flying heights comparable topresently achievable flying heights.

The sensing means are capable of ascertaining a physical quantitydepending on the transversal speed of the liquid surrounding thesupporting vertical struts of the hydrofoil crafts due to the horizontalorbital motion of the waves. The control means which may be of any kindare suitable for controlling, for example by means of a servomechanismsaid angular strut position.

Said sensing means may comprise mechanical, electric, hydraulic andpneumatic elements or other suitable members of any kind arranged on thehull or on a suitable immersed portion of the strut and able toascertain the amount and direction of the transversal flow or one of itseffects. For example, the sensing means could measure the mechanicalstresses produced by an exciting force or depending on the transversalflow, or the pressure or any other function or effect of the transversalspeed of said flow on the immersed struts.

The physical value representing for example speed, force, acceleration,displacement or the like and sensed in response to the transversal orlateral speed of the fluid flow is preferably transformed into anyelectric, electronic mechanical, hydraulic or displacing signal whichmay be conveniently amplified for controlling said servo-mechanism in aclosed-loop circuit whereby to automatically adjust the instantaneousangular strut position either by rotating the axis of null lift of thevertical struts or by causing a suitable transversal variation in thelift thereof. 7

According to the invention there is further provided lift varying meanscomprising means for blowing of air or water along one or more of thesupporting vertical struts, said blowing being directed transversally tothe hull-and having an intensity and direction depending on theintensity and direction of said transversal speed whereby the varying ofthe strut left is controlled in such a way as to remove said disturbingforce.

In another embodiment according to the invention at least one flap-typevertical aileron is suitably arranged on one or more of said strutssupporting the hull. Said aileron is controlled so as to produce a liftvariation for balancing the transversal force produced by saidtransversal speed of the flow.

Said sensing means comprise, for example, extensimeters which mayoperate mechanically, pneumatically, or electric-ally on the strut or inthe hull, to check 7 any deformation of the carrying struts caused bysaid transversal speed of the fluid.

BRIEF DESCRIPTION OF THE DRAWINGS with reference to the accompanyingdrawings, wherein:

FIG. 1 shows the cross section of a hydrofoil craft raised to a height Habove the water surface or horizontal X-X; I

. FIG. 2 shows a partial lateral view of said hydrofoil craft with avertical strut hinged to the hull along an axis I- -I;

FIG. 3 shows the strut as viewed in the direction III- III of FIG. 2said strut being rockable ortiltable about the axis I-I;

FIG. 4 shows a diagram of the resultant speed V +v of the water flow;

FIG. 5 illustrates a section along line V-V of FIG. 2;

FIGS. 6 and 7 show a vertical strut fixed on the hull, and provided witha hinged vertical flap; and

FIGS. 8 and 9 illustrate longidutinal side and top views respectively,of a hydrofoil craft with completely immersed wings;

FIG. 10 illustrates the actuating means of FIG. 5 as applied to the flapof FIG. 7;

FIG. 11 is a view similar to FIG. 6 wherein the flap has been replacedby fluid'jet holes in the side walls of the strut;

FIG. 12 shows the actuating means of FIG. 5 for 3 operating the fluidjets in FIG. 1 1.

If, as is diagrammatically shown in FIG. 1, the hull l is transversallyinclined by an angle 3 relative to the horizontal XX, the weight Q asexpressed in percent of the displacement and which bears on the wingpair 3, resolves into forces F, and Q Where the struts 2 are integrallyor rigidly attached to the hull as in the prior art 1, the force Fl willcause a moment MS F, Z, wherein Z is the vertical distance between thehorizontal plane extending through the center of gravity G of the craftand the horizontal plane in which a force F is effective on the strut 2;said force F being exerted on the surfaces of the struts mostly byhorizontal, orbital motion of the waves. On the other hand, where thevertical strut 2 is hinged to the hull as shown in FIGS. 2 and 3according to the invention, namely in front of the thrust center andalong an axis I--I, the strut 2 is free to rock about a hinge 4. As aresult, the force F, will not generate any listing moment, but willtranslate laterally the hull l with a speed component (v). In fact, asshown in FIG. 4, the combination of the speed V of the longitudinalmovement of the hydrofoil and the speed (v) of the lateral or sidedisplacement of the hydrofoil will define a resultant V +v. A ratherslant angle a is included between the direction Y-Y of forward motionand the direction of said resultant. The strut 2 will position itself atsuch angle a relative to the forward movement direction Y-Y, whereby theeffect of the force F1 is cancelled. The foregoing considerations applyto any one of the various transversal exciting forces, caused forexample by any orbital horizontal side motions of the waves. That is, aflow with the speed (v), as in the first example, will cause a resultantV +v and a corresponding angle a and the rocking strut will immediatelyassume such tilted position that from the beginning any effect of suchforces as F or F, is avoided and therefore the listing moments caused bysaid forces are also avoided.

It is however to be considered that the vertical strut 2, which is freeto tilt about the hinge along the axis 1-- I, represents in itspractical embodiment relative to the water flow a rocking system withits own mass, inertia and damping factor so as to alter the effects itreceives from the flow speed (v), and thus the strut will assumepositions according to angles which do not necessarily correspond tosaid angle a resulting due to components V and v. The vertical strut 2may also position itself at an angle corresponding to the angle but notwithin suitable response times whereby the effects of forces F and F,are not cancelled completely but only a part or fraction thereof. Thesystem as above described may be called an open-cycle system which issubject to disturbances and undesirable phase shifts of various kinds.

For example when one of the wings 3, as shown in FIG. 3, is subject toan accidental and non-symmetrically effective force T acting at a forcearm N with respect to the direction Y-Y, there will be a disturbingmoment T times N with respect to the hinge axis which will tend to tiltthe strut 2 to an angle which is indepem dent of the flow speed (v) orof such forces as F or F,, whereby a subsequent listing moment of thehull is caused.

In order to remove the above disadvantages, it has been found to benecessary to control the tilting angles of the struts 2 exclusively inresponse to the flow speed be in response to sensing the mechanicalstress effects caused by the force F, which is a function of the flowspeed (v), and transforming such stress effects into a control signalwhich is used to control any mechanical, hydraulic, electric,electronic, pneumatic or composite closed loop'system, so as to cancelthe effects of said excitation forces by positioning the strut 2 atsuitable angles a corresponding to the null lift axis of the strutoutline.

An embodiment of a closed loop system is shown, for example, in FIG. 5.The strut 2 is shown in .section along the line V-V of FIG. 2. Due to aneffect to the flow speed (v) the force F causes a flexion of the strut2, whereby the strut 2 assumes a flexed position as indicated by thedash-dotted line in FIG. 5. Such a flexion may be mechanicallysubstantial in its infinitesimal values Af as indicated by the movementof the free upper end of a sheet or flat member 12 the lower end ofwhich is integral with said strut so that the free upper end is freelydisplaceable in a transversal direction.

The infinitesimal movement values Af control through' a follower member11" a hydraulic pilot servovalve 11 which is attached to the strut 2.The servovalve 11 is connected through hydraulic conduits 11' to anactuating element such as a piston cylinder device pivoted to the strut2 as at 10. The arrangement is such that the strut 2 is always tilted ina direction which tends to reduce AF to zero and thus to close theservovalve and thereby the response cycle. Consequently, as soon as theforce F tends to begin, its effect is immediately cancelled through anangular tilting of the strut 2 about the axis II.

Such angular tilting or rotation of the strut 2 by the piston cylinderdevice 10 will position the strut 2 at said angle a which, as stated, isequal to the angle resulting from the composition of flows V and v atthe very moment considered. Stated differently, the instantaneous,tilted position of the strut will always correspond to the instantaneousangle necessary for proper compensation of any list moments.

The effect of the flow speed (v) may be ascertained or sensed evendirectly, for example by introducing a sensing means of any type into asuitable immersed portion of the strut 2 and transmitting the value orsignal sensed to the above described control device or to any othersimilar control device.

The mechanical stresses generated by the force F, or the pressurescaused by the flow speed (v) or any effect or function caused by theflow speed (v) on said strut 2 may be transformed from any movement dueto compression or acceleration into a respective electric or electronicsignal which, suitably amplified, constitutes the control function of aclosed cycle automatic control circuit for tilting the strut 2 to therequired angle.

The desired effect of cancelling the listing moments obtained bycancelling the force F or any function of the flow speed (v) will beobtained by controlling the tilting angles of the strut 2 regardlesswhere the hinging axis II is located relative to the strut. For example,the hinges 4 may be located anywhere along the chord axis of the strutor along the longitudinal front face of the strut 2 as shown in FIG. 2,or along axes parallel to the chord axis of the strut.

Thus, the hinge axis I-I may be located in front of said strut, thus,e.g., between the strut and the stem, or at the center of the strut, orat the rear edge of the strut, for example between the strut and thestern, or even laterally of the strut. Different examples forpositioning the hinge axis are shown in FIGS. 2, 3 and 8. According toanother embodiment, the compensation for the transversal listing momentsis obtained by balancing the force F by means of vertical flaps 13,shown in FIGS. 6 and 7, or by blowing air, water or the like, or byusing any device capable of performing a variation of the controlledlift. In such a case the strut 2 is formed as an integral part of thehull 1.

As described above, the exciting force F, acting on the immersed part ofvertical strut means 2, FIG. 5, can by sensing means such as the flatmember 12 be transduced into a displacement signal Af, suitable to thecontrol of a hydraulic pilot servovalve 11 for actuating the pistoncylinder device 10. The control takes place through a follower member11". If cylinder 10, as seen in FIG. 10 is connected to flap 13 by alink 10' soas to rotate the flap 13 about its hinge axis 2b by an angleB in the same direction and proportional in amplitude to F, at the startof the signal Af, a hydrodynamic force will develop in the immersed partof the vertical strut means, having a value F X (B) opposite to F, whichshall produce a force resulting on the vertical strut means Fy=,F F (B)within the limits required to compensate the list.

Assuming FB/Fy= n, in which (n) has an arbitrary value, preferablybetween 2 and 6, and FB/F const., and F=Fy -l7 F (B) we have: F (B) nFyand F Fy nFy =Fy (1+n) and therefore F (B)/F =const. n-Fy /(l+n)Fyn/(n+l) which is the percentage of force reduced by the lift controlwith the flap 13.

According to another lift control arrangement shown in FIGS. 11 and 12 anumber of holes 1' and 1" are provided in the two sides of verticalstrut means 2 along a vertical line. These holes are suitably connectedthrough ducts 2', 2" and pipes 3, 3" to the two outlets of adistribution valve 4" to which the fluid under pressure flows through aduct 5. The valve 4" is controlled by the cylinder 10 by means of alinkrod 4a so as to cause a fluid which can be either air or water underpressure to flow to holes 1' or 1" in either direction and correspondingin sense and being proportional to the intensity of signal Afrepresenting the force F. When in all the holes of one side of thevertical strut fluid sprays are formed, the lift of the immersed part ofsaid vertical strut is altered so as to develop a F (B) force oppositeto F as in the previous case with the flap.

The above device may be generally used on any hydrofoil craft havingcompletely immersed wings or comprising a combination of completelyimmersed and/or partly immersed wings.

Further the hull may be provided with one or more or all strutscontrolled according to the invention by a closed cycle system or acomposite arrangement.

FIGS. 8 and 9 show for example, a hydrofoil craft provided with twoforward struts 14 and 16 which are hinged and controlled as described. Asimple vertical strut which is not tiltable is provided at the sternwhere it may be arranged to comprise a zed-type transmission for apropeller or the feeding conduits of a hydrojet. Neither thetransmission for driving propeller nor the hydrojet for propelling thecraft are part of the invention.

Assuming that said forward controlled hinged struts bear 60 percent ofthe total displacement, the hydrofoil.

craft will have to be provided with a known transversal stabilizationsystem for balancing the listing moments caused by the vertical andhorizontal orbital motion of the waves on a fixed stern strut or struts.Consequently, the hydrofoil craft will be able to rise 60 percent higherthan present hydrofoil crafts although only the same straighteningmoment is applied.

If in the device of the present invention it is assumed that 2 is theminimum value of n, the result is:

Le, 67 percent of the listing forces due to horizontal orbital movementsacting upon controlled vertical strut means are eliminated. Forinstance, supposing to control the lift only at the two fore verticalstrut means of the hydrofoil and that said strut means dimensions areproportional to the weight lying on the wings, for instance 60 percentof the weight on the fore wings, the resulting force of the whole shallbe Fy=(33/100) (60/100) -F+(40/l00) F 2 (60/100) F in which F is the.total force acting on the immersed part of the three vertical strutmeans. Therefore for the same listing moment (Ms) due to the horizontalorbital movements we have:

Ms=F Z= Fy-Zy where and consequently H is proportional to Z: 1.67 l-l,that is to say Hy can be 67 percent higher than H.

Hence, if the lift variation'is variation is controlled on all threevertical strut means, for the same 67percent reduction coefficient theresult is:

where Hy 311.

The important advance in the art achieved by eliminating the effects ofsuch forces as F, is seen in the better navigation and comfort as wellas in lower stresses for the structure of the craft at flight heightscorresponding to those of conventional crafts as well as at higherflight heights whereby higher waves are better overcome.

Further, since the present invention requires lower straighteningmoments for reducing the excitations caused by the vertical orbitalmotions, the distance B between the struts shown in FIG. 1 may bereduced to the lowest possible distance. For example, when only onecontrolled tilting strut is arranged at one half the and and

hull length said excitations will be nearly cancelled. It is also animportant advantage of the invention that the possibility of reducing Bto a desired small value, allows one to construct hulls with the mostsuitable ration between the length and the width for hydrofoil craftsemploying the present invention. On the other hand, in order to increasethe straightening moment in conventional hydrofoil boats, B must beincreased thereby reducing the ratio between the length and width of thehull. The reducing of this ratio unfavorably influences the features ofthe hydrofoil craft itself. The invention has overcome this drawback ina surprisingly simple manner.

It is to be understood that the invention is not limited to the examplesshown. It is intended to cover all modifications and equivalents withinthe scope of the appended claims.

What I claim is:

1. In a list preventing device for water crafts having a hull, hydrofoilmeans and strut means for connecting the hydrofoil means to the hull,the improvement comprising sensing means located for sensing a physicalquantity produced by horizontal orbital motion of a wave which iseffective transversally relative to the longitudinal hull axis, controlmeans operatively connected to said sensing means, and strut actuatingmeans operatively connected to said control means, whereby the actuatingmeans-are automatically controlled in response to and in proportion tothe instantaneous value and direction of said physical quantity foreliminating from the beginning even before it can affect the hull, anyeffect of said physical quantity by virtual rotation of the null liftaxis of the vertical strut means.

2. The list preventing device according to claim 1, further comprisingmeans for hinging said strut means to said hull, and comprising meansfor hinging said strut means to said hull, and means for connecting saidactuating means to said hinged strut means.

3. The list preventing device according to claim 1, wherein said strutmeans have a trailing edge said device further comprising flap meansforming part of said trailing edge of said strut means, hinge means forhinging the flap means to the respective strut means, and means forconnecting the actuating means to said hinged flap means.

4. 'The list preventing device according to claim 3, wherein thevertical height of the flap means corresponds substantially to that ofthe length of the vertical strut means below said hull.

5.-The listpreventing device according to claim 1, wherein said sensingmeans comprise an elongated flat member located inside said strut means,said flat member having a lower end rigidly connected to said strutmeans and a freely movable upper end for indicating any flection of thestrut means under the effect of said physical quantity, said sensingmeans further comprising a follower position for cooperation with theupper end of the flat member and connected to said control means foroperating the control means in response to the instantaneously sensedvalue and direction of said physical quantity.

6. The list preventingdevice according to claim 2, wherein said controlmeans is a hydraulic servo-valve connected to said actuating means.

varying the lift of said struts, said jet means being positioned fordirecting a fluid stream along said strut means and transverselyrelative to the hull, said jet means being operatively connected to saidcontrol means, for controlling the intensity and. direction of saidfluid stream in response to said physical quantity for removing theeffects of said quantity.

1. In a list preventing device for water crafts having a hull, hydrofoilmeans and strut means for connecting the hydrofoil means to the hull,the improvement comprising sensing means located for sensing a physicalquantity produced by horizontal orbital motion of a wave which iseffective transversally relative to the longitudinal hull axis, controlmeans operatively connected to said sensing means, and strut actuatingmeans operatively connected to said control means, whereby the actuatingmeans are automatically controlled in response to and in proportion tothe instantaneous value and direction of said physical quantity foreliminating from the beginning even before it can affect the hull, anyeffect of said physical quantity by virtual rotation of the null liftaxis of the vertical strut means.
 2. The list preventing deviceaccording to claim 1, further comprising means for hinging said strutmeans to said hull, and comprising means for hinging said strut means tosaid hull, and means for connecting said actuating means to said hingedstrut means.
 3. The list preventing device according to claim 1, whereinsaid strut means have a trailing edge said device further comprisingflap means forming part of said trailing edge of said strut means, hingemeans for hinging the flap means to the respective strut means, andmeans for connecting the actuating means to said hinged flap means. 4.The list preventing device according to claim 3, wherein the verticalheight of the flap means corresponds substantially to that of the lengthof the vertical strut means below said hull.
 5. The list preventingdevice according to claim 1, wherein said sensing means comprise anelongated flat member located inside said strut means, said flat memberhaving a lower end rigidly connected to said strut means and a freelymovable upper end for indicating any flection of the strut means underthe effect of said physical quantity, said sensing means furthercomprising a follower position for cooperation with the upper end of theflat member and connected to said control means for operating thecontrol means in response to the instantaneously sensed value anddirection of said physical quantity.
 6. The list preventing deviceaccording to claim 2, wherein said control means is a hydraulicservo-valve coNnected to said actuating means.
 7. The list preventingdevice according to claim 6, wherein said actuating means comprise apiston cylinder arrangement, said device further comprising hydraulicconduit means for interconnecting said piston cylinder arrangement andsaid hydraulic servo-valve to form a closed loop automatic followercircuit including said sensing means.
 8. The list preventing deviceaccording to claim 1, wherein said actuating means comprise jet meansfor varying the lift of said struts, said jet means being positioned fordirecting a fluid stream along said strut means and transverselyrelative to the hull, said jet means being operatively connected to saidcontrol means, for controlling the intensity and direction of said fluidstream in response to said physical quantity for removing the effects ofsaid quantity.